Sasha CampbellThose tiny, immobile pests that appear like small bumps on your plants are likely scale insects.
They feed by sucking sap from plants, causing them to wilt and appear sickly. Additionally, the leaves may turn yellow and drop off.
Scale insects are of the order Hemiptera [1]. They can cause serious damage to the garden, greenhouse, and houseplants, depending on the extent of the infestation.
Both armored scale and soft scale insects can affect indoor plants, fruit trees, and ornamentals. Therefore, early control is important.
These pests are identified by tiny, shell-like bumps clustered along plant stems. Many scale insects, especially soft scales, excrete a sticky substance called honeydew, which can lead to black sooty mold growth on plants.
Signs of Scale Infestation
- Sticky honeydew.
- Ant activity.
- Black sooty mold.
- Tiny bumps on stems/leaves.
- Poor plant growth.
- Yellowing or premature dropping of leaves.
How to Get Rid of Scale on Plants Naturally
Below are some common home remedies and natural solutions that you can try.
1. Rub Them Off
If the problem is small, this is the most inexpensive way to control scale insects. Therefore, this method works well for small infestations of houseplants.
An old toothbrush is a good tool for scraping or rubbing the pests off the stems.
Alternatively, a slightly abrasive sponge or cotton swab dabbed in rubbing alcohol should do the trick. However, test rubbing alcohol on a small part of the plant first, as some plants may be sensitive to it.
Also, check under leaves where they may be hiding. Afterward, you can spray with an organic insecticide to prevent reinfestation.
2. Horticultural Oil
Purchase horticultural oil at the garden store or online. It is also known as summer oil or dormant oil. Spray all infected plants with the product as per the manufacturer’s instructions.
The oil smothers the insects. However, repeated applications may be necessary to eliminate an infestation. Choose a dry day with low humidity and no high winds to apply it to the infected plants.
Alternatively, a DIY horticultural oil solution might be less expensive.
To make a homemade horticultural oil spray, first mix 1 cup of vegetable oil with 1 tablespoon of liquid soap. Then combine 1 tablespoon of this concentrate with 1 cup of water before spraying.
Finally, shake well and coat the affected plants with your homemade scale spray. Use the measurement as a guide for larger portions.
3. Pruning
Pruning is a great practice to remove tree scale insects, as an infestation may require drastic action.
If you act fast, this home remedy will stop pests at an early stage, preventing them from spreading to other areas. Additionally, there will be no honeydew to attract other pests.
Afterward, dispose of heavily infested plant parts in the trash or remove them from the garden area. Pruning may also strengthen plants and help them resist further damage.
4. Beneficial Insects
Using beneficial insects is one of the main biological methods for controlling pest infestations. Predatory insects such as lady beetles, lacewings, and parasitic wasps may help control some scale species [2].
Plus, you can purchase most of these beneficial insects at various garden centers or online.
It is also possible to encourage them to visit your garden. Plant flowers like yarrow and cosmos to attract them.
5. Neem Oil
Neem comes from the seeds of the neem tree. Farmers have been using it for many years as a natural pesticide.
Mix 2 teaspoons of liquid soap with 2 tablespoons of neem oil and 1 gallon of warm water to use neem oil for scale insects. Finally, shake well and spray the infested plants.
You can also find this natural treatment as a concentrate. It comes mixed with other active ingredients in organic commercial sprays.
Neem oil works by smothering scale insects and disrupting their feeding and life cycle.
6. Insecticidal Soap
Insecticidal soap is another excellent home remedy for treating plant scales naturally. So, let’s make a homemade insecticidal soap spray to kill scales.
Pure liquid castile soap, combined with water and vegetable oil, can do the trick.
Combine 5 tablespoons of liquid soap with 2 tablespoons of vegetable oil, then add 1 gallon of warm water. Shake well.
Finally, spray the DIY scale-infestation spray on the affected plants. You can also purchase commercially available insecticidal soap.
7. Bug Blaster
This method uses a strong blast of water to remove scale insects from plants.
The apparatus consists of a ‘wand’ and a nozzle. It is designed to dislodge soft-bodied pests from plants using a strong stream of water without harming your plants.
Bug Blaster is also economical with water, and any excess on plants will be usefully absorbed. However, if the pests return, repeat the process.
Water sprays work best on young scale crawlers and light infestations.
8. Azadirachtin
Azadirachtin is a commonly used organic insecticide for controlling scale insects on plants.
It disrupts the insects’ normal life cycle. The pests will eventually die.
Additionally, when used properly, azadirachtin is generally considered less harmful to many beneficial insects and mammals than synthetic pesticides.
9. Essentria IC-3
This commercial product controls many pests.
Essentria IC-3 contains a blend of essential oils and other ingredients. It is a multipurpose natural insecticide containing rosemary oil, peppermint oil, and geraniol.
This plant-scale treatment can be used for spraying or misting, as directed by the manufacturer. It can also be used to drench surfaces and paths to eliminate or prevent pest infestations.
Essentria IC-3 may help control some scale insects on plants. Additionally, with caution, you can use it directly on cattle, horses, and chickens.
It also works against many other crawling and flying insect pests.
10. Diatomaceous Earth (DE)
DE may help control young crawling scale insects.
Diatomaceous earth damages the protective outer layer of soft-bodied insects, leading to dehydration and death. However, it is generally less effective against mature scales protected by hard coverings.
Diatomaceous earth is widely available in garden stores and online. As a preventive measure, dust it on plant surfaces and around the base.
How to Prevent Scale Insects
- Inspect new plants before bringing them home.
- Avoid overfertilizing plants.
- Prune weak or crowded growth.
- Encourage beneficial insects.
- Keep plants healthy and stress-free.
Frequently Asked Questions
Will Dawn dish soap kill scale?
Dawn dish soap may help control some soft scale insects. However, detergents may damage sensitive plants.
A true insecticidal soap or pure liquid castile soap is usually safer.
What causes scale insects on plants?
Scale insects often appear on stressed or weakened plants. They may spread from nearby infested plants or from new plants brought into the garden or home.
Can a plant recover from scale insects?
Yes, many plants can recover if the infestation is treated early. Pruning damaged areas and using natural treatments may help restore plant health.
Are scale insects harmful to humans?
Scale insects do not bite or harm humans.
What plants do scale insects attack?
Scale insects attack many plants, including houseplants, fruit trees, shrubs, ornamentals, and vegetables. Citrus plants are also vulnerable.
Does neem oil kill scale insects?
Yes, neem oil may help kill scale insects. It works by smothering them and disrupting their feeding and development.
Repeated applications are often necessary.
What is the fastest way to get rid of scale on plants?
For light infestations, rubbing the insects off by hand works well. Then, spray with horticultural oil or insecticidal soap. This method is often the quickest solution.
Heavy infestations may require pruning and repeated treatments.
Takeaway
Scale damage to plants may be unsightly. The pests may also affect houseplants, garden flowers, shrubs, fruit trees, and vegetable crops.
Try the natural remedies above to eliminate them and keep your plants pest-free.
I have hard scale insects on my water lilies in the koi pond. They are on the lily pads and stems. How did this happen and how to get rid of them?